Usutu virus: a Flavivirus on the rise amid COVID-19 and monkeypox
Authors: Parul C. Gupta, Prakasini Satapathy, Ankur Gupta, Mubarick N. Asumah, Bijaya K Padhi
Journal: International Journal of Surgery (2023)

Dear Editor, Global warming and globalization have facilitated the emergence and propagation of infectious diseases. The distribution patterns of parasites and arthropod vectors have changed, resulting in imported pathogens in new geological regions1. Usutu virus (USUV) has recently drawn the interest of scientists due to its widespread proliferation and endemization throughout Europe2. USUV, a mosquito-borne Flavivirus, was initially isolated in South Africa (Usutu River, Swaziland) in 1959 from Culex neavei and Mansonia aurites mosquitoes3. It is an enveloped RNA virus that is still preserved in the environment in bird reservoirs which play the role of amplifying hosts2. Over the past two decades, USUV has expanded across a significant portion of the European continent, primarily triggering severe avian mortality with a massive resurgence of bird infections recently documented across Europe4. Most frequently, USUV infection in humans is believed to be asymptomatic or to result in minor clinical symptoms. However, there have been a few reports of neurological problems, including encephalitis or meningoencephalitis5. USUV, West Nile virus, and Japanese encephalitis virus have several characteristics in common, including close phylogenetic similarity and an analogous ecosystem, with co-circulation regularly occurring in nature. Co-infections in people are conceivable and likely. They may make diagnosis more difficult. Furthermore, because these two viruses are so similar, 'cross-immunity' is a possibility. Other viruses belonging to the Flaviviridae family include the dengue virus, yellow fever virus, and Zika virus6. Clinical features and diagnosis USUV has been found in mammals in addition to birds like bats, deer, dogs, horses, wild boars, rodents, and shrew species, suggesting a probable zoonotic spillover7,8. Humans and other mammals are deemed as incidental or 'dead-end' hosts2. Neurotropism and neuroinvasive disease are seen in both immunocompromised and immunocompetent patients2. Clinical manifestations in the limited number of humans so far include fever, rash, headache, jaundice, encephalitis, meningoencephalitis, and facial paralysis9–13. Some individuals might be asymptomatic, with viral antibodies being accidentally detected in blood samples of blood donors using sequencing techniques14. Recently, two cases of USUV infection were detected in France. Both these cases involved aboriginal patients, that is, the patients who become ill without leaving the country. This can possibly be due to transmission by migratory birds. In 2016, a person in Montpellier patient contracted this virus. He presented in the emergency with neuroinvasive disease and facial paralysis15. Humans USUV infection is diagnosed using multiple techniques, including the detection of viral RNA in blood and cerebrospinal fluid, (ii) virus isolation in cell culture, and/or (iii) detecting anti-USUV antibodies (IgM and IgG) in patients' serum and cerebrospinal fluid using enzyme-linked immunosorbent assay or immunofluorescence tests. Public health concerns Although few sceptics continue to dispute the fact of worldwide climatic alteration, there is no reservation about the fact that various types of developing arbovirus illnesses have emerged dramatically over the last five decades or so15. After the emergence of the coronavirus, monkeypox virus, Langya virus, and the BtSY2 virus, the USUV has resurfaced recently. There is substantial proof that the epidemiological situation of contagious illnesses is unpredictable and 'unstoppable' because of climatical, environmental, and human-allied aspects. The development and propagation of novel diseases in new locales, and the re-advent of well-established or forgotten pathogens with modified virulence, diffusion traits, and alternative host/tissue inhabitation, are probable outcomes. A range of additional elements has been key determining factors of emergent pandemics and epidemics in several circumstances. These comprise of increased human tourism; industrial haulage; urbanization; deforestation; land retrieval; irrigation schemes; increased human, livestock, and arthropod populaces; and governmental or military procedures which result in bulk human evacuations16. For reducing the burden of vector-borne diseases, insecticides have been used since time immemorial. Their use has resulted in resistance development, spreading toxic metabolites in the food chain, and deleterious effects on nontarget creatures. However, recently entomopathogenic fungi–based lure and kill tactics using biopolymers can be a safe, reliable, and eco-friendly vector management tool17. Presently, there are no vaccines or antivirals to prevent and control human USUV infection. However, vaccination against any Flavivirus-like tick-borne encephalitis virus, Japanese encephalitis, or yellow fever might provide some 'cross-immunity' to this virus. Clinicians and virologists, specifically in endemic areas during summer months must contemplate a probable infectious trigger secondary to USUV infection in meningoencephalitis cases of undetermined etiology10. The way forward Engaging mosquito-control procedures quickly and communicating pertinent knowledge to regional populations can help prevent the spread of mosquito-borne flaviviruses. Pesticide-free methodologies like entomopathogenic fungi can prove to be a promising biocontrol mechanism17. Remote sensing satellite imaging methods using ecological parameters like the concentration of green vegetation can be used to predict the advent patterns of mosquitoes. These robust epidemiological surveillance systems can assist in the establishment of more effective vector control programs18. Given the likelihood that USUV spreading tendencies will continue, continual multidisciplinary involvement of infectious disease specialists, entomologists, veterinary personnel, and public health professionals must be carried out to raise understanding and adopt suitable supervising and deterrence techniques to thwart the spread of this emerging arboviral contagion to virus-free zones in a timely manner19. Ethical approval and informed consent Ethical approval and informed consent were not required for this study. Sources of Funding There was no source of funding for this research. Authors' contribution All authors contributed equally. Conflicts of interest disclosure The authors declare that they have no financial conflict of interest with regard to the content of this report. Research registration unique identifying number (UIN) Not applicable. Guarantor All authors. Data Availability Data sharing is not applicable to this article as no new data were created.